1. Field of the Invention
This invention relates to aircraft safety and more particularly to a system for optically monitoring an aircraft and recording the resulting images on a crash-survivable recording system. The invention further relates to a method of capturing images of the exterior or interior of an aircraft and displaying them to crew members or transferring them to ground stations while in flight or on the ground.
2. Background
The airline or air carrier industry transports a fairly large volume of travelers to many destinations every day. One of the primary concerns of airline passengers, as well as various governmental agencies charged with transportation safety, is the safety of aircraft which are provided by a multitude of carriers and aircraft manufacturers. Over time, the general public, and most airline passengers, have developed a positive feeling for airline safety. Statistically speaking, air travel has been safer than other presumably safe activities. As an example, in 1963 there were 18 times as many people involved in gun related accidents, 67 times as many in fires, and 360 times as many in automobile accidents as were involved in aircraft related accidents. In 1964, only 1 in 405,000 air travelers were involved in an accident. However, during the 1984 through 1985 time period, this perception of safety was challenged by an unusually large increase in the number of accidents or air disasters, as well as the notoriety with which they were reported.
Government agencies such as the National Transportation Safety Board and the Federal Aviation Agency investigate the events of every airline accident and attempt to ferret out the root cause to allay public fears that the accident will repeat itself on another flight. Accident investigations attempt to pinpoint whether factors such as design error, pilot error, improper maintenance, or nature were the cause. In this manner, specific recommendations can be made to correct a persistent or latent problem. However, it has become increasingly difficult to ascertain the true cause of many crashes.
The principle tool in aircraft accident investigations are flight recorders which are commonly known as "black boxes". There are two "boxes" on every commercial aircraft, one containing a recorder for instrument data and the other for voice, with each being engineered to withstand the rigors of a catastrophic aircraft crash. These recorders provide information such as air speed, altitude, heading, vertical acceleration etc., which tells something about the aircraft's condition and conversations of the crew or those in the "flight deck" area which indicates what the crew "thought" was happening.
In using the data provided by the black box recorders, several facts have become apparent. First, the data is actually more limited than desired for a complete analysis. Instrumentation data, which may be false in complex system failures, may indicate symptoms but not causes. As an example, indication of hydraulic line failure and loss of control is typically the result of other structural damage and not the cause. Internal instrumentation only monitors internal control systems to indicate what external structural or control elements "should" be doing but not what they actually are doing.
Second, even if a particular structural failure is known to occur, it can often be the symptom of several alternative damage scenerios. Using current investigation techniques there is no way of knowing what was actually occurring on the exterior surfaces of the aircraft to better determine the sequence of events.
Third, it appears that the difference between successful and unsuccessful reactions by a crew to certain damage profiles is more a matter of chance than certainty. The crew must quickly "guess" at the cause of a problem, or the physical state of affairs on the outer structure of an aircraft and hope that they are right. Evidence in some airline crashes suggests that pilots may have had time to counteract a given problem if they only knew the true nature of the damage. It is critical for a pilot to know the full extent of damage since many types of damage, say to hydraulic lines or elevator sections may exhibit the same control response at first. Certain systems such as flap extensions also have a lag between control exercise and response leading to over compensation in emergencies. The crew responses may not be directed in many situations to the correct problem. If the pilot chooses the wrong maneuver or power correction, the problems are greatly increased.
Pilots using traditional instrumentation and ordinary flight experience simply cannot know the true extent of external damage. There is currently no external monitoring system for aircraft to inform the pilot of the nature of damage which he is trying to counteract. The only technique available is for a crew member to walk though the aircraft for visual inspection or, if weather allows, fly by an airport observation point and receive confirmation from the ground as to the damage. Besides being a costly (fuel) procedure, this approach pre-supposes that there is time for such observation. Generally no such opportunity exists.
A factor of increasing importance in complicating air carrier safety is an ever increasing threat of human intervention in the form of sabotage, hijacking, or terrorism. Even if an aircraft is properly designed, manufactured, maintained, and operated, these forms of human activity make air transportation a dangerous or risky form of travel for many each year.
In the case of sabotage, it is extremely difficult to provide adequate security monitoring of an aircraft in large busy terminal areas using conventional techniques. During refueling, loading, cleaning and maintenance many people may approach a given aircraft. It is simply not practical to use the traditional "guards" to monitor all personnel during this time for large numbers of aircraft. In addition, previously "cleared" personnel are often influenced by others to change.
In the case of terrorism, no adequate system exists for monitoring the presence of known or prospective terrorist group members. Additionally, there is no system for monitoring the events of a terrorist or other type of hijacking while an aircraft is flight. This leads to a total dependence upon information provided over the radio from personnel that are either under threat of death or are themselves perpetrators. The lack of any or even some accurate information prevents most government agencies or police forces from adequately responding to a hijacking.
In order to increase the general safety of air travel and counter terrorist or sabotage activities, what is needed is a new system to: provide pilots with in flight visual damage assessment information; record external and internal optical image data in a crash survivable form; and provide security monitoring information for the interior or exterior. The system must be associated with each aircraft individually but also capable of providing information to centralized monitoring points for further viewing or analysis.